No. 2, where the 200-foot section of Well No. 1 is missing, extraordinarily low 

 interval velocities are observed. This velocity of 8000 feet per second is not 

 representative of the geologic section and apparently is the velocity of the brec- 

 ciated fault zone. Additional evidence has been observed recently to indicate 

 that faults can be identified by anomalous low velocity response of this type. 



The continuous velocity log provides the geophysicist with a method for de- 

 termining the origin of seismic reflections. Figures 21-15, 21-16, and 21-17 are 



COMPARISON OF CONTINUOUS 

 VELOCITY LOG AND SEISMIC RECORD 



W 60 n/*c 



9300 



Ft /SEC 



J0H* _----- 

 GEORGETOWN 



16000 FT/SEC 



Figure 21-16. Comparison of velocity log and seismic record. 



< B 

 =^. c 



.-^E D 



_=J_ | E 



B. TIMPAS- 

 T. CARL1LE 



CRETACEOUS 



'0' SAND 

 ■M'SAND 

 LYONS ]} PENNSYLVANIAN 



VELOCITY LOG 



Figure 21-17. Velocity log and synthesized reflection record. 



421 



